Refrigerating apparatus



March 4, 1941. H. J. MOLLENBERG 2,233,633

REFRIGERATING APPARATUS Filed Dec. 29, 1959 O O o] INVENTOl Harold J Mol/enberg BY l ATTORNE? I Patented Mar. '4, 4

UNITED STATES PATENT OFFICE 2,233,633 nnrnrcnnnmc APPARATUS Harold I. must, Kenmore, N. Y. Application December 29, 1939, Serial-No. 31l,561 '1 Claims. (01.62-3) This invention relates to a system of mechanical refrigeration, and it has particular reference to the provision of regulating and control r means in a compression-expansion refrigerating systemwhereby the condensing of compressed refrigerant is effected under varying operating conditions with a minimum of energy.

In the common and .well known compressioncondensing-expansion system of refrigeration, it has heretofore been proposed to condense the compressed and warm refrigerant vapors by means of an air or water cooled condenser, or by means of a condenser cooled by both air and water. The use of water is indicated because of its higher specific heat, while the use of ,air is advantageous when the apparatus is of relatively small size, in order to conserve the costs incident to water cooling. Apantfrom' this factor, it is obvious that refrigeration plants must operate under variousclimatic conditions-the air temperature may be considerably below freezing, or it may be very warm, and thus the ability of air to absorb heat from the compressed refrigerant is a variable.

In industrial plants, in which air cannot be relied upon for the condenser cooling medium, water is usually supplied from city mains, and must be paid for, or the water is taken from a coninvolving a factor of cost. In any event, the cost of supplying water to the condensers has long been recognized as significant, and an item which must be taken into account when estimating the initial and operating costs of the system;

Of the various types of water cooled condensers, one frequently specified is that known as the evaporative or atmospheric condenser, in which a shower of water is directed over the pipes forming the condensing coil, while air is inducted or 0 blown over the coil in an opposite direction. The unsaturated air acts to evaporate the water, with a resulting cooling effect, and thus increases the capacity of the air to extract heat from the hot compressed gases flowing through the coil. 15 Certain difficulties are encountered, however, in using this type of condenser, particularly in installations in which the load is variable. Moreover', even when operating under a substantially constant load, the efliciency of the condenser varies over wide limits, due, among other things, to changes in the temperature and relative humidity of the air, and changes in'the temperature of the cooling water. A condensingplant designed to coact effectively with the compressors under anticipated maximum load thus becomes overbalanced when the 'load is decreased, or overloaded if less condensing capacity is initially specifled, with the results of decreasing operating ef- 0 ficiencies, and wasting cooling water and power all venient pond or well, and must be pumped, again necessary to operate the water pump 'and air blower.

In order to eliminate losses of this nature, the present invention contemplates the modification of .the over-all condenser capacity, and the power 1 input thereto, in response to variations in compressor loadand the factors affecting the heat absorption capacity of the cooling media, and this, in a practical way, may be effectively and inexpensively accomplished by controlling, in sequentiai manner, the quantities of supplied cooling media in response to the compressor head pressure. The efiective capacity of the condensing system is, therefore, automatically adjusted to the total load on the compressors, ,in a manner which regulates the head pressure within those limits at which the compressor is emcient. Not only is a proper thermal balance thereby obtained between the high and low sides of the refrigeration system, but the operating costs for power are considerably reduced, and a full automatic con- .trol system permits of reduction of expenses for supervision to a minimum.

A typical embodiment of the invention is illustrated in the accompanying drawing, refer-red to in the following description explanatory of the principles of the; invention, and wherein:

Fig. 1 is a layout of a refrigerating plant utilizing the features hereinafter claimed, and

Fig. 2 is a wiring diagram showing a mode 0 connecting the control instrumental-ities into the system.

Referring first to Fig. 1, there are shown four water-cooled compressors, l0, H, H, and I3, designed to compress ammonia vapor or other suitable refrigerant, and which are automatically or manually cut into or out of service, depending on the demand of the expansion side of the system.

. other convenient point where it is exposed to the air. After being cooled in the condenser, the re-' frigeran't flows through pipe line I! to a receiver l8, for distribution to the expansion col-ls l9, and thence through the suction line 2| to the inlet of the'compressor, thereby completing the refrigerant circuit.

It will be understood that the expander IS, in-'- dicated in dotted lines, may be any type, as for air cooling in an air conditioning circuit, open pipes as in a cold storage room, or pipes submerged in a brine bath for indirect cooling, and the coils may be placed in different rooms or 10- calities. As the load on these coils varies, more or less compressor capacity is demanded, and it cally responsive .to such load. This type of control is, of course, old and well understood, and does not constitute the essence of the present invention. For that reason, further description will not be made here, it simply being intended to point out how the amount of refrigerant, and hence the compressor capacity, is a variable affecting the duty imposed on .the high side of the system, and on which side the regulation of this invention primarily occurs.

The extraction of heat from the compression side of the system is effected by means of both air and water. A water main 25, connected to the city supply lines. or a local pumping systemor tower, supplies water under pressure to the compressor and condenser. A branch line 26 connects the main 25 to a distributor 21, from which extend lines 28 to admit the water to the jackets of the cylinders of the various compressors I0, l3. The warm water flowing from the cylinder jackets'discharges into a collector line 29 connected to a riser 3|, which in turn empties into a tank 32 used for recirculating the condenser water. Thus, it will be seen that the compressor cooling water, instead of being run to waste, as is customary, is returned to the sys-' tem under some conditions of operation, and in fact it may be said that the arrangement is such that the warm compressor water is utilized as the make-up source for the condenser. I

Regulation of the cylinder jacket water is effected by'thennally controlled pressure responsive valves, which may be of any common and known type. The thermal bulb is, of'course, at-

tached to the discharge lines 29, while the valve itself is interposed in the line 28, so that the will be apparent that the use ofthewarm compressor water for condenser make-up purposes is permissible.

The tank 32 is also supplied directly with water from the main 25 through a lateral 35 whose discharge opening is controlled by a float valve 36. If the tank level becomes too low for any cause, the float drops, opening the line 35 to admit water until the desired level is reached, whereupon the line 35 is closed. Any overflow from ghe tank 32 is discharged through the drain line Water contained in the tank 32 is admitted to the suction side of a pump 4| through suction line 42, while the pump efliuent flows past check valve 43 into a riser 44 which terminates in a spray manifold 45 disposed above the coil 15 of the condenser IS. The pump 4|, which is driven by'a motor 45 in a manner hereinafter described, thus supplies cooling water to the condenser coils, in accordance with the known principles of operating an atmospheric condenser. The water draining from the coils I5 is collected in a basin 4! for return to the tank 32 through the line 48.

Under some operating conditions, there is a it is desired to drain the riser 44 and manifold blower or fan 56, driven by a motor 51. The lowe andpermitting the pump to supply water fro the tank 32 to such extent as the developed hea temperature intermediate the temperatures be proportioned to the duty imposed on the ba densing plant by the compressors. Under cond more refrigerant is circulated, an increasing d water in the riser 44 forces the check valve open and permits the riser to drain. This expedient is simple, and it eliminates the necessity for interposing a high pressure valve between the line: 44 and 52.

Mounted above the coils I5 and the customar eliminator plates 55 of the condenser I5 is an ai portion ofthe condenser casing is, of course open, as indicated by the reference numeral 58 so that, when the motor 5'| is operated, a draf of air is induced toflow upwardly over the coil l5, to cool the refrigerant contained therein, an for discharge through suitable opening provide atthe top of the condenser.

Attention is invited to the fact that the wate main 25 is also directly connected to the riser 4 through a branch 59, in which is disposed a sole noid controlled shut-off valve 5 I. When the valv 6| is open, cold supply water is forced directl into the riser 44. It should be understood tha the pump 4| is preferably of the centrifugal ty thus making by-pass connections unnecessa pressure permits. Thus, with valve 5| open, an pump 4| in operation, the water supplied to th coils I5 is a mixture of water from the main 2 and from the tank 32, and may therefore be at each source of supply. In other words, a mixe water supply is used under the condition 1 stated, as a means of conserving the amount water demanded from the main line 25. i

In order to obtain the amount of cooling d sired in the condenser, and which must, of cours tery of compressors, it may first be noted th condenser cooling media may be of four kind namely, natural draft air, circulating throug the condenser it when all other supplies are c off; forced draft air supplied by the fan 56; wat supplied by the pump 4|; and water supplied the pump 4| and the main 25.

As so listed, these media are approximately their order of increasing cooling capacity,,an they have been so listed to consider them co jointly with the demands imposed on the co tions of light-load in the expansion system, o viously there is a minimum of refrigerant, terms of mass or quality, to be cooled and co densed, and operation of thecondensing plant full capacity would therefore render the co pressor performance erratic and ineificient.

mand is imposed on the condensing plant. Broa ly considered, it may therefore be said that t present invention contemplates the continuo modulation of the condensing plant, to provi for it that capacity best suited to the duty 1 posed on or by the compressors.

The compression of the refrigerant is reflecte practically, by an increase in pressure and to perature, and for efficient operation, it isdewinter weather, the cold air itself, either when sirable to maintain the discharge or condensing pressure within reasonably close limits. If, for example, the condensing plant is unable to cool 5 the compressed refrigeranfi properly, the ap-.

parent result is an increase iii\pressure. Accordingly, the modulation of the -'-cpndensing plant is made responsive to step by stepchanges in the pressure existing in the compresso r *disl0 charge line H. A

ceive the pressure connections for-three pressure-operated mercoid switches, 65, 68, and 61, which are located respectively in the circuits for '15 the fan motor 51', the water pump motor 4|, and

the solenoid valve 6|. Inasmuch as the circuits themselves are standard, and are made with the usual commercial starting boxes and the like, no detailed description is deemed necessary. It is sufficient to say that the mercoid switches close when the pressure in the line I4 reaches various predetermined values, and when. the switches are thrown the circuits in which they'are disposed are closed, thus energizing the motor 10- cated in each circuit.

1 say 135 pounds gauge, all of the switches are open, and there is neither a forced draft of air or flow of water over the 'coils I! of the con-' denser. when the head pressure reaches this predetermined value, the switch 85 is closed, thus completing thecircuit for the air blower 40 motor 51, and causing a blast of air, to beinductedthrough'the vent 88. When the head pressure increases to say 150 pounds. the switch 66 is closed, thus adding to the cooling capacity the results obtained by forcing water through the spray nozzles 45, by operation of the motor 46. If through any circumstance the head pressure should continue to rise, to say '180'p'ounds, then the third switch 6] is also closed.to excite .the solenoid valve 6|, thereby opening the valve and admitting additional quantities of colderwater from the main 25.- I

' Conversely, as the pressure is reduced by the .action ois-thefcondenser, .the solenoid valve is set to close at'a pressure of say 170 pounds, and the switch in turn is set to open when the pressure drops to say 140 pounds. The switch may be set within somewhat closer limits, as

for example 130 -pounds-these ranges being ob- 1 tained, of course, by setting of the high and low The operation of the system may be further considered for an installation such as a brewery,

in which the expansion coil load is subject to wide variations, located in a relatively northern community, where the air temperature may vary from below zero Fahrenheit in the winter to ninety degrees in the summer. With such variations, it is of course obvious that the quality of cooling air changes considerably, and, in

For this purpose, the line H is tapped to reflowing over the coils l5 by simple. convection, or through induced draft, may extract as much heat from the compressed refrigerant as warmer air and water could in mid-summer. For another operating condition, one may consider a hot summer day, with a high relative humidity and an appreciable increase in. the temperature of the cooling water, and which may, of course,

. be coupled with a heavy loadion the expansion coils. In such case, a condensing plant designed to operate always on forced air draft and water spray can become overloaded, as shown by the rise in head pressure, and therefore means have been providedz to introduce the, coldest available water to the system, despite the possible increased overflow loss.

For any set of conditions, however, reliance is placed on using the cheapest cooling medium to its fullest capacity, before calling into service the next cooling medium. This is made possible by controlling the application of the various media in a step-by-step method, in accordance with increases in' refrigerant high side pressures,

and herein the invention diifers from older systems, in which the entire condensing capacity. was intermittently either called in, or ,was cut out of service.

Analyses of installations made in accordance with the invention have showed that considerable savings in cost of cooling water and-power, together with some reduction in the size of the condensing plant, are efl'ected with thepresent invention. In fact, even when water is supplied directlywfrom themain 25, its heat absorption capacity is conserved by returning it to the tank 32, rather than to waste-the waste water in such case being partially composed of the warmer water localized in the tank 32.

It will, of course, be understood by those skilled in the art that the various control instrumentalities referred to herein may be of the common and usual known types, and that hand valves or switches may be interposed in the various refrigerant, water, and electric circuits auxiliaries form no part of the present invention, however, as it has been one purpose here to describe the invention in its most effective form in a fully automatic installation. It will moreover be appreciated that while the'invention has been described'with reference to one specific embodiment, variations and modifications'may be made within the scope thereof, as encompassed by the followingclaims.

I claim: f

1. I a refrigerating apparatus including a compr ssor, a condenser coil, and an evaporator connected in a closed circuit, means for admitv existing in the compressor, and means 'responsive to the pressure existingat the compressor v for' controlling-'the operation of's'aid pump.

2. In a refrigerating apparatus including a compressor, a condenser coil, and an evaporator connected in a closed circuit, a supply of water,

pumpmeans for admitting water from the supply to .the surface of the condenser coil, a riser auxiliary drain means hydraulically connectingthe riser pipe to the supply for draining said pipe only when the pump is out of operation.

3. In a water cooled refrigerating system ineluding a compressor, a condenser coil, and an tank, a

evaporator connected in a closed circuit, means for recirculating cooling water around the condenser coil, said means including a local storage pump, a discharge line fromthe pump to the surface of the coil, a drain for returning water discharged by the pump to the tank, and an overflow drain for the tank; valve means for admitting make-up water to the tank from an extraneous source; other valve means for admitting water from said extraneous source to said condenser coil surface directly thereby to admit water to said recirculating means at a point other than said tank, whereby water admitted directly from said extraneous source to the con-- denser coil surface is mixed with recirculating water contained in said tank, and water escaping from said overflow drain is mixed water from said extraneous source and said recirculating circuit. V

4. In a refrigerating apparatus including a compressor, a condenser coil, and an evaporator connected ina closed circuit, and wherein there is provided, in combination with said coil, means for supplying convection currents of air, a forced draft of air, and water to the surface of said coil for cooling refrigerant contained therein,

, blower means for creating the forced draft of air, pump means for supplying the water, means for operating each of the blower means and pump means independently of each other, means responsive to a predetermined pressure condi tion in excess of minimum operating pressure conditions in the refrigerant line connecting the compressor and condenser coil for controlling the operation of the blower means, and means responsive to predetermined pressure conditions in said refrigerant line higher than said first-- named pressure condition for controlling the operation of said pump means, whereby the condenser coilis cooled by the sequential application of, convenction air, forced draft air, and water in response to progressive increases in the pressure of refrigerant between the compressor and condenser coil.

5. In a refrigerating apparatus including a compressor, a condenser coil, andan evaporator connected in a closed circuit, and wherein variations in the load imposed on the evaporator change the work done by the compressor, means "for varying the cooling capacity of the condenser coil in response to pressure conditions existing in the refrigerant between the compressor and the condenser coil, said last named means comprising: means for supplying convec-v tion currents of air to the surface of the condenser coil, a blower for supplying a forced draft of air to said surface, a motor for operating the blower, a switch responsive to predetermined pressure conditions in the hot refrigerant for opening and closing the circuit for the blowermotor, a local supply of cooling water, apump for spraying the cooling water over the surface of the coil, a motor for operating the pump, and a switch also responsive to pressure conditions in the hot refrigerant'for opening and closin the circuit for the pump motor, said last named switch operating to close the pump motor-circuit upon the occurrence of pressure conditions in excess of the conditionat which the blower motor operates, and means'for admitting makeup water to the local supply of cooling water in response to the extent to which the pump motor is operated and the local water supply is thereby diminished in heat extraction quality.

6. In a refrigerating apparatus including a compressor, a condenser coil, and an evaporator connected in a closed circuit, and wherein the evaporator is subject to varying loads and the hot refrigerant flowing through the condenser coil is subject to heat exchange with'bo'th air and vwater of variable quality,'means for regulating the supply of cooling media to the surface of the condenser coil in response to variations in the evaporator and compressor load and the change in quality of the cooling media; said regulating means comprising: means for supplying a convection current of air to the surface of the condenser coil, 9. motor-driven'blower for supplying a forced draft of air, a local supply of water and a motoriven pump for supplying water therefrom to the surface, and an extraneous supply of water for said surfacei the convection air supplying means being operative .under all conditions of operation, pressureresponsive electrically actuated means for independently controlling the operation motor-driven blower, the motor-driven pump, andthe extraneous water supply, said electrically actuated means being sequentially operated by rising pressure in the refrigerant circuit between the compressor and-the condenser coil in stepby-step order.

7. In a refrigerating apparatus including a water-cooled compressor, a condenser coil subject to, air and water cooling, and an evaporator connected in closed circuit, means for supplying forced draft air to the surface of the condenser coil when the refrigerant pressure between the compressor and coil reach a predetermined range of values, pump, a spray pipe and 'a drain line hydraulically connected in a local closed circuit for supplying water to the surface of the condenser coil,

admit water therethrough upon the occurrence of the a water .tank containing water, a

halved conof pressure conditions in the refrigerant between the compressor and the condenser coil in excess of the presure conditions at which the water pump is operated, and an overflow line from the tank to remove excess quantities of water introduced into the local circuit from said extraneous source.

. HAROLD J. MOLLENBERG. 

